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    <ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../intern.html">Inter Modules</a></li><li><a href="index.html">final</a></li><li><a href="index.html#5">Chapter 5: C</a></li><li><b>C Global Variables</b></li></ul></div>
<p class="purpose">Global variables translated to C.</p>

<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. </b></p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::initialise</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">CGlobals::initialise</span></span>:<br/>Final C - <a href="5-fnc.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">DECLARE_VARIABLES_MTID</span><span class="plain-syntax">, </span><a href="5-cgv.html#SP3" class="function-link"><span class="function-syntax">CGlobals::declare_variables</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">METHOD_ADD</span><span class="plain-syntax">(</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="constant-syntax">EVALUATE_VARIABLE_MTID</span><span class="plain-syntax">, </span><a href="5-cgv.html#SP5" class="function-link"><span class="function-syntax">CGlobals::evaluate_variable</span></a><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>

<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">C_generation_variables_data</span><span class="plain-syntax"> {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">no_variables</span><span class="plain-syntax">;</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">C_generation_variables_data</span><span class="plain-syntax">;</span>

<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::initialise_data</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">CGlobals::initialise_data</span></span>:<br/>Final C - <a href="5-fnc.html#SP4">&#167;4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">C_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">vardata</span><span class="plain-syntax">.</span><span class="element-syntax">no_variables</span><span class="plain-syntax">) = </span><span class="constant-syntax">1</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<ul class="endnotetexts"><li>The structure C_generation_variables_data is private to this section.</li></ul>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. </b>The basic scheme is this: the global Inter variables are going to have
their values stored in an array, so to identify which variable you are reading
or writing, you need an index (i.e., position) in that array.
</p>

<p class="commentary">The main thing we need to compile is a (static) array of initial values for
these variables, so that a new process can be initialised. But we must also
define constants to refer to their positions in the array.
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::begin</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">CGlobals::begin</span></span>:<br/>Final C - <a href="5-fnc.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">}</span>

<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::end</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">CGlobals::end</span></span>:<br/>Final C - <a href="5-fnc.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_ids_and_maxima_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"#define i7_no_variables %d\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">C_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">vardata</span><span class="plain-syntax">.</span><span class="element-syntax">no_variables</span><span class="plain-syntax">));</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"i7word_t i7_initial_variable_values[i7_no_variables];\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. </b>We will assign the global variables unique index numbers 0, 1, 2, ..., with
the special variable <span class="extract"><span class="extract-syntax">self</span></span> given index 0. Note that <span class="extract"><span class="extract-syntax">self</span></span> always exists,
but has no Inter declaration node.
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::declare_variables</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">CGlobals::declare_variables</span></span>:<br/><a href="5-cgv.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">linked_list</span><span class="plain-syntax"> *</span><span class="identifier-syntax">L</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_globals_array_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"i7word_t i7_initial_variable_values[i7_no_variables] = {\n"</span><span class="plain-syntax">);</span>

<span class="plain-syntax">    </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_1" class="named-paragraph-link"><span class="named-paragraph">Define a constant for the self position in the globals array</span><span class="named-paragraph-number">3.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_3" class="named-paragraph-link"><span class="named-paragraph">Add the initial value for self to the globals array</span><span class="named-paragraph-number">3.3</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_5" class="named-paragraph-link"><span class="named-paragraph">Define a more legible constant for self to the header target</span><span class="named-paragraph-number">3.5</span></a></span><span class="plain-syntax">;</span>

<span class="plain-syntax">    </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">N</span><span class="plain-syntax"> = </span><span class="constant-syntax">1</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">LOOP_OVER_LINKED_LIST</span><span class="plain-syntax">(</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">, </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax">, </span><span class="identifier-syntax">L</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">identifier</span><span class="plain-syntax"> = </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">);</span>
<span class="plain-syntax">        </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_2" class="named-paragraph-link"><span class="named-paragraph">Define a constant for this position in the globals array</span><span class="named-paragraph-number">3.2</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">        </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_4" class="named-paragraph-link"><span class="named-paragraph">Add the initial value to the globals array</span><span class="named-paragraph-number">3.4</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">        </span><span class="named-paragraph-container code-font"><a href="5-cgv.html#SP3_6" class="named-paragraph-link"><span class="named-paragraph">Define a more legible constant for the header target</span><span class="named-paragraph-number">3.6</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">N</span><span class="plain-syntax">++;</span>
<span class="plain-syntax">    }</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">C_GEN_DATA</span><span class="plain-syntax">(</span><span class="identifier-syntax">vardata</span><span class="plain-syntax">.</span><span class="element-syntax">no_variables</span><span class="plain-syntax">) = </span><span class="identifier-syntax">N</span><span class="plain-syntax">;</span>

<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"};\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3_1" class="paragraph-anchor"></a><b>&#167;3.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Define a constant for the self position in the globals array</span><span class="named-paragraph-number">3.1</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_ids_and_maxima_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"#define "</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="5-cnm.html#SP5" class="function-link"><span class="function-syntax">CNamespace::mangle_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"self"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" 0\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP3_2" class="paragraph-anchor"></a><b>&#167;3.2. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Define a constant for this position in the globals array</span><span class="named-paragraph-number">3.2</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_predeclarations_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"#define "</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="5-cnm.html#SP5" class="function-link"><span class="function-syntax">CNamespace::mangle_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">identifier</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" %d\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">N</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP3_3" class="paragraph-anchor"></a><b>&#167;3.3. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Add the initial value for self to the globals array</span><span class="named-paragraph-number">3.3</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_globals_array_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"  0 /* self */\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP3_4" class="paragraph-anchor"></a><b>&#167;3.4. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Add the initial value to the globals array</span><span class="named-paragraph-number">3.4</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_globals_array_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">", "</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">definition</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">inter_tree_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax"> = </span><span class="identifier-syntax">var_name</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">definition</span><span class="plain-syntax">;</span>
<span class="plain-syntax">        </span><a href="2-cg.html#SP18" class="function-link"><span class="function-syntax">CodeGen::pair</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">, </span><span class="identifier-syntax">VariableInstruction::value</span><span class="plain-syntax">(</span><span class="identifier-syntax">P</span><span class="plain-syntax">));</span>
<span class="plain-syntax">    } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"0"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    }</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" /* %S */\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">identifier</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP3_5" class="paragraph-anchor"></a><b>&#167;3.5. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Define a more legible constant for self to the header target</span><span class="named-paragraph-number">3.5</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><a href="5-cgv.html#SP4" class="function-link"><span class="function-syntax">CGlobals::define_header_constant_for_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"self"</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP3_6" class="paragraph-anchor"></a><b>&#167;3.6. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Define a more legible constant for the header target</span><span class="named-paragraph-number">3.6</span></span><span class="comment-syntax"> =</span>
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">name</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Metadata::optional_textual</span><span class="plain-syntax">(</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">InterPackage::container</span><span class="plain-syntax">(</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">-&gt;</span><span class="identifier-syntax">definition</span><span class="plain-syntax">), </span><span class="identifier-syntax">I</span><span class="string-syntax">"^name"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">name</span><span class="plain-syntax">)</span>
<span class="plain-syntax">        </span><a href="5-cgv.html#SP4" class="function-link"><span class="function-syntax">CGlobals::define_header_constant_for_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">name</span><span class="plain-syntax">, </span><span class="identifier-syntax">N</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">else</span>
<span class="plain-syntax">        </span><a href="5-cgv.html#SP4" class="function-link"><span class="function-syntax">CGlobals::define_header_constant_for_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">identifier</span><span class="plain-syntax">, </span><span class="identifier-syntax">N</span><span class="plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="5-cgv.html#SP3">&#167;3</a>.</li></ul>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. </b></p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::define_header_constant_for_variable</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">CGlobals::define_header_constant_for_variable</span></span>:<br/><a href="5-cgv.html#SP3_5">&#167;3.5</a>, <a href="5-cgv.html#SP3_6">&#167;3.6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">,</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">id</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">segmentation_pos</span><span class="plain-syntax"> </span><span class="identifier-syntax">saved</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::select</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="constant-syntax">c_variable_symbols_I7CGS</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"#define %S %d\n"</span><span class="plain-syntax">, </span><a href="5-fnc.html#SP7" class="function-link"><span class="function-syntax">CTarget::symbols_header_identifier</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">I</span><span class="string-syntax">"V"</span><span class="plain-syntax">, </span><span class="identifier-syntax">var_name</span><span class="plain-syntax">), </span><span class="identifier-syntax">id</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="2-cg.html#SP12" class="function-link"><span class="function-syntax">CodeGen::deselect</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">, </span><span class="identifier-syntax">saved</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. </b>Within a process <span class="extract"><span class="extract-syntax">proc</span></span>, the current value of variable <span class="extract"><span class="extract-syntax">i</span></span> is <span class="extract"><span class="extract-syntax">proc-&gt;state.variables[i]</span></span>.
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">CGlobals::evaluate_variable</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">CGlobals::evaluate_variable</span></span>:<br/><a href="5-cgv.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">code_generator</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gtr</span><span class="plain-syntax">, </span><span class="reserved-syntax">code_generation</span><span class="plain-syntax"> *</span><span class="identifier-syntax">gen</span><span class="plain-syntax">,</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">inter_symbol</span><span class="plain-syntax"> *</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">as_reference</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">OUT</span><span class="plain-syntax"> = </span><a href="2-cg.html#SP14" class="function-link"><span class="function-syntax">CodeGen::current</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">gen</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"proc-&gt;state.variables["</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><a href="5-cnm.html#SP5" class="function-link"><span class="function-syntax">CNamespace::mangle_variable</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">InterSymbol::trans</span><span class="plain-syntax">(</span><span class="identifier-syntax">var_name</span><span class="plain-syntax">));</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"]"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b>Finally, this function, part of the C library, initialises the variables for a
newly-starting process.
</p>

<pre class="Extracts-displayed-code all-displayed-code code-font">
<span class="Extracts-identifier-syntax">void</span><span class="Extracts-plain-syntax"> </span><span class="Extracts-identifier-syntax">i7_initialise_variables</span><span class="Extracts-plain-syntax">(</span><span class="Extracts-identifier-syntax">i7process_t</span><span class="Extracts-plain-syntax"> *</span><span class="Extracts-identifier-syntax">proc</span><span class="Extracts-plain-syntax">);</span>
</pre>
<ul class="endnotetexts"><li>This is part of the extract file inform7_clib.h.</li></ul>
<pre class="Extracts-displayed-code all-displayed-code code-font">
<span class="Extracts-identifier-syntax">void</span><span class="Extracts-plain-syntax"> </span><span class="Extracts-identifier-syntax">i7_initialise_variables</span><span class="Extracts-plain-syntax">(</span><span class="Extracts-identifier-syntax">i7process_t</span><span class="Extracts-plain-syntax"> *</span><span class="Extracts-identifier-syntax">proc</span><span class="Extracts-plain-syntax">) {</span>
<span class="Extracts-plain-syntax">    </span><span class="Extracts-identifier-syntax">proc</span><span class="Extracts-plain-syntax">-&gt;</span><span class="Extracts-identifier-syntax">state</span><span class="Extracts-plain-syntax">.</span><span class="Extracts-identifier-syntax">variables</span><span class="Extracts-plain-syntax"> = </span><span class="Extracts-identifier-syntax">i7_calloc</span><span class="Extracts-plain-syntax">(</span><span class="Extracts-identifier-syntax">proc</span><span class="Extracts-plain-syntax">, </span><span class="Extracts-identifier-syntax">i7_no_variables</span><span class="Extracts-plain-syntax">, </span><span class="Extracts-identifier-syntax">sizeof</span><span class="Extracts-plain-syntax">(</span><span class="Extracts-identifier-syntax">i7word_t</span><span class="Extracts-plain-syntax">));</span>
<span class="Extracts-plain-syntax">    </span><span class="Extracts-identifier-syntax">for</span><span class="Extracts-plain-syntax"> (</span><span class="Extracts-identifier-syntax">int</span><span class="Extracts-plain-syntax"> </span><span class="Extracts-identifier-syntax">i</span><span class="Extracts-plain-syntax">=0; </span><span class="Extracts-identifier-syntax">i</span><span class="Extracts-plain-syntax">&lt;</span><span class="Extracts-identifier-syntax">i7_no_variables</span><span class="Extracts-plain-syntax">; </span><span class="Extracts-identifier-syntax">i</span><span class="Extracts-plain-syntax">++)</span>
<span class="Extracts-plain-syntax">        </span><span class="Extracts-identifier-syntax">proc</span><span class="Extracts-plain-syntax">-&gt;</span><span class="Extracts-identifier-syntax">state</span><span class="Extracts-plain-syntax">.</span><span class="Extracts-identifier-syntax">variables</span><span class="Extracts-plain-syntax">[</span><span class="Extracts-identifier-syntax">i</span><span class="Extracts-plain-syntax">] = </span><span class="Extracts-identifier-syntax">i7_initial_variable_values</span><span class="Extracts-plain-syntax">[</span><span class="Extracts-identifier-syntax">i</span><span class="Extracts-plain-syntax">];</span>
<span class="Extracts-plain-syntax">}</span>
</pre>
<ul class="endnotetexts"><li>This is part of the extract file inform7_clib.c.</li></ul>
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